The present invention relates to a pant-type absorbent article (such as those often referred to as xe2x80x9ctapeless-typexe2x80x9d or xe2x80x9ctraining pant typexe2x80x9d) which includes a pair of leg holes for leg insertion, and a waist hole for encircling a waist portion of a body. The present invention further relates to a method for manufacturing such an absorbent article. The absorbent article of this type may be used for infant and adult diapers, feminine sanitary products and the like.
Absorbent articles, particularly infant and adult diapers, have recently gained increased acceptance from consumers for their advantageous characteristics of stability during use and reduced leakage.
In order for tapeless absorbent articles to fully exhibit their advantageous characteristics, they need to fit snugly to a user""s body, particularly at leg hole portions thereof. To this end, such tapeless absorbent articles have elastically stretchable ruffles or leg gathers, as they are generally called, along peripheries of the leg holes.
One example of such tapeless absorbent articles with leg gathers is disclosed in Japanese Patent Application No. 3-195558. Two sets of elastic members are attached along the peripheries of the leg holes to form leg gathers. Each set of elastic members extends along one leg hole from a front end of the leg hole to a midpoint of the leg hole, and continuously extends transversely of a central region (crotch region) of the article to a midpoint of the other leg hole to form a cross-over portion. From the midpoint of the other leg hole, each set of elastic members further extends therealong to a rear end of the other leg hole. Those two sets of elastic members are arranged so as to define a somewhat X-shaped configuration.
Such arrangement of the elastic members advantageously facilitates a continuous manufacturing process of the absorbent articles. Specifically, a liquid impermeable sheet in a continuous web form is continuously transported in one direction. Continuous elastic strands are fed onto the sheet in a sinusoidal configuration for securement thereto. The resultant combination is cut at a predetermined interval to form a composite back sheet incorporating the elastic members secured thereto.
The elastic members arranged along peripheries of the leg holes in the aforementioned, conventional tapeless absorbent article function to form leg gathers therealong. However, the elastic members extending transversely of the crotch region not only are non-functional waste material but cause the absorbent article to deform at the crotch region when they elastically contract.
An attempt to remedy such disadvantages has been made by adjusting a stretching or contracting rate of the elastic members to be lower at the crotch region than along the leg holes. However, it complicates a manufacturing process, and lowers productivity to intermittently change the stretching rate of the elastic members during the continuous manufacturing process wherein the continuous elastic members are fed along predetermined lines on a web for securement thereto. The elastic members tend to impair flexibility and comfort to a wearer during use at the crotch region of the absorbent article where it is desired to be sufficiently flexible to provide comfort to the wearer during use. Furthermore, added elastic material for the elastic members is required at the cross-over region when they are secured to the back sheet at the lower stretching rate. This results in an increased material use as those elastic members at the cross-over region are not necessary.
The two sets of elastic members secured to the back sheet create bundle-like bunches at the crotch region of the absorbent article, which results in the article having a poor appearance.
It is an object of the present invention to provide an improved absorbent article which is capable of eliminating the above-described disadvantages that conventional articles possess, so that any undesirable deformation of the crotch region due to the contracting force of the elastic members is avoided, and flexibility thereat is insured.
It is an other object of the present invention to provide a method for manufacturing such an absorbent article.
In accordance with the present invention, there is provided an absorbent article which is provided with a main body having a waist hole and a pair of leg holes. The main body comprises a liquid impermeable back sheet, a liquid permeable top sheet and an absorbent core interposed between the back sheet and the top sheet. The absorbent article is further provided with a waist gather disposed along the waist hole, and a leg gather disposed along each of the pair of leg holes.
The top sheet may include two layers of sheet materials, and two sets of elastic members interposed between the two sheets of material to form a composite sheet. The first of the two sets of elastic members extend along a periphery of a first leg hole from a front end thereof to a midpoint thereof, and continuously extend transversely to a midpoint of a second leg hole to form a cross-over portion having a central section spaced inwardly from and intermediate the leg holes. From the midpoint of the second leg hole, the first set of elastic members extends to the front end of the second leg hole. The second of the two sets of elastic members extends along a periphery of the first leg hole from a rear end thereof to a mid-point thereof, and continuously extends transversely to a mid-point of the second leg hole to form a cross-over portion having a central section spaced inwardly from and intermediate the leg holes. From the mid-point of the second leg hole the second set of elastic members extends to the rear end of the second leg hole, so that the two sets of elastic members are arranged to define an X-shaped configuration. The two sets of the elastic members are secured in a stretched state to the sheet materials along areas that extend along the peripheries of the leg holes. The central sections of the cross-over portions thereof are not secured to the sheet materials, and are separated so that they snap back toward cross portions of the two sets of the elastic members to define tail portions extending from the cross portions.
As such, the absorbent article in accordance with the present-invention has the elastic members extending around leg holes to form leg gathers. The elastic members do not cross the crotch region of the article. Accordingly, the absorbent article provides a snug fit and comfort to the wearer during use, with its leg gathers effectively preventing leakage from the article. The leg elastic members are not secured to the back sheet, so that the absorbent article provides a good appearance.
In one embodiment of the present invention, the top sheet has a through aperture in the crotch region of the absorbent article. The aperture serves as an inlet void of a pocket for communicating urine and fecal material into the pocket defined between the top sheet and the back sheet. This provides comfort to the wearer during use.
The present invention further provides a method for manufacturing a tapeless absorbent article which comprises a main body having a waist hole and a pair of leg holes and comprising a liquid permeable top sheet, a liquid impermeable back sheet and an absorbent core interposed between the top sheet and the back sheet, a waist gather disposed along the waist hole, and a leg gather disposed along each of the leg holes.
Two sets of elastic members in their stretched conditions are positioned, between two sheets of material in elongated web forms, in overlapping sinusoidal configurations with an inverted phase relation to each other, so that the two sets of elastic members define a number of elongated oblong areas therebetween. The elastic members are bonded to the sheet material in alternate ones of the oblong areas, and are cut or separated in the oblong areas in which they are not secured so that they snap back toward crossing, or intersecting, portions thereof.
The top sheet is combined with the back sheet prior to bi-folding of the resultant combination along a transverse center line. The bi-folded resultant combination is severed along predetermined cutting lines.
The present method can advantageously provide a highly productive process which is capable of securing elastic members to sheet materials without varying the feed rate of the sheet materials.
One embodiment of the present invention will be explained hereinafter with reference to the drawings.